pH-Sensitive Theranostic Nanoparticles for Targeting Bacteria with Fluorescence Imaging and Dual-Modal Antimicrobial Therapy

Bacterial infections with severely damaging consequences are serious threats to the public healthcare system. A pH-sensitive theranostic system was fabricated for targeting bacteria with fluorescence imaging and dual-modal antimicrobial therapy (cationic and photodynamic therapies). Poly(poly(ethylene glycol) methyl ether methacrylate)-b-poly(2-(diisopropylamino) ethyl methacrylate-co-2-hydroxyethyl methacrylate)-chlorin e6 (PPEGMA-b-P(DPA-co-HEMA)-Ce6) was synthesized via reversible addition–fragmentation chain transfer (RAFT) polymerization and post-modification. The self-assembled PPEGMA-b-P(DPA-co-HEMA)-Ce6 nanoparticles (NPs) with a mean diameter of about 78 nm and polydispersity index of 0.27 were obtained through the dialysis method. The surface potential of PPEGMA-b-P(DPA-co-HEMA)-Ce6 NPs can undergo changes from negative (−1.45 mV) at pH 7.4 to highly positive (+11.6 mV) at pH 6.0, as characterized by the zetasizer. The extent of interaction between the PPEGMA-b-P(DPA-co-HEMA)-Ce6 NPs and bacteri...